Commit graph

76 commits

Author SHA1 Message Date
Linus Torvalds
b0cbc861a3 Revert "ACPI battery: fix async boot oops"
This reverts commit 5d38258ec0, since the
underlying problem got fixed properly in the previous commit ("async:
Fix module loading async-work regression").

Cc: Arkadiusz Miskiewicz <a.miskiewicz@gmail.com>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
Cc: Len Brown <len.brown@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-11 12:45:20 -07:00
Vegard Nossum
5d38258ec0 ACPI battery: fix async boot oops
> BUG: unable to handle kernel NULL pointer dereference at (null)

What happens is that the battery module's init sections are being freed
before the async callback (which was marked __init) has run. This theory
is supported by the fact that the bad RIP value is a vmalloc address.

The immediate fix is to make this a non-init call.

(A better long-term fix is of course to wait with init-section unloading
until a module's async initcalls have been run, which would allow us to
discard this function which is still only run once, after all. Perhaps a
new async_initcall() function for the async/module API, if this is needed
for other modules in the future?)

Reported-by: Arkadiusz Miskiewicz <a.miskiewicz@gmail.com>
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
Tested-by: Alessandro Suardi <alessandro.suardi@gmail.com>
Tested-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Len Brown <len.brown@intel.com>
2009-04-07 16:24:54 -04:00
Len Brown
478c6a43fc Merge branch 'linus' into release
Conflicts:
	arch/x86/kernel/cpu/cpufreq/longhaul.c

Signed-off-by: Len Brown <len.brown@intel.com>
2009-04-05 02:14:15 -04:00
Len Brown
e2fae0abf6 Merge branch 'constify' into release 2009-04-05 01:51:16 -04:00
Len Brown
59b17bf6ea Merge branch 'async-battery' into release
Conflicts:
	drivers/acpi/Makefile

Signed-off-by: Len Brown <len.brown@intel.com>
2009-04-05 01:48:46 -04:00
Arjan van de Ven
0f66af5301 ACPI: battery: asynchronous init
The battery driver tends to take quite some time to initialize
(100ms-300ms is quite typical).
This patch initializes the batter driver asynchronously, so that other
things in the kernel can initialize in parallel to this 300 msec.

As part of this, the battery driver had to move to the back
of the ACPI init order (hence the Makefile change).
Without this move, the next ACPI driver would just block
on the ACPI/devicee layer semaphores until the battery driver was
done anyway, not gaining any boot time.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
2009-04-04 12:51:17 -04:00
Jan Engelhardt
070d8eb1f6 ACPI: constify VFTs (1/2)
Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Len Brown <len.brown@intel.com>
2009-04-03 23:14:40 -04:00
Alexey Dobriyan
99b7623380 proc 2/2: remove struct proc_dir_entry::owner
Setting ->owner as done currently (pde->owner = THIS_MODULE) is racy
as correctly noted at bug #12454. Someone can lookup entry with NULL
->owner, thus not pinning enything, and release it later resulting
in module refcount underflow.

We can keep ->owner and supply it at registration time like ->proc_fops
and ->data.

But this leaves ->owner as easy-manipulative field (just one C assignment)
and somebody will forget to unpin previous/pin current module when
switching ->owner. ->proc_fops is declared as "const" which should give
some thoughts.

->read_proc/->write_proc were just fixed to not require ->owner for
protection.

rmmod'ed directories will be empty and return "." and ".." -- no harm.
And directories with tricky enough readdir and lookup shouldn't be modular.
We definitely don't want such modular code.

Removing ->owner will also make PDE smaller.

So, let's nuke it.

Kudos to Jeff Layton for reminding about this, let's say, oversight.

http://bugzilla.kernel.org/show_bug.cgi?id=12454

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
2009-03-31 01:14:44 +04:00
Alexey Starikovskiy
7faa144a51 ACPI: battery: add power_{now,avg} properties to power_class
ACPI has smart batteries, which work in units of energy and measure
rate of (dis)charge as power, thus it is not appropriate to export it
as a current_now. Current_now will still be exported to allow
for userland applications to match.

Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
2009-03-27 22:23:52 -04:00
Richard Hughes
56f382a087 battery: don't assume we are fully charged when not charging or discharging
On hardware like the T61 it can take a couple of seconds for the battery
to start charging after the power is connected, and we incorrectly tell
userspace that we are fully charged, and then go back to charging.

Only mark a battery as fully charged when the preset charge matches either
the last full charge, or the design charge.

http://bugzilla.kernel.org/show_bug.cgi?id=12632

Signed-off-by: Richard Hughes <hughsient@gmail.com>
Acked-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Acked-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>
2009-02-21 12:36:19 -05:00
Alexey Starikovskiy
50b178512b Newly inserted battery might differ from one just removed, so
update of battery info fields is required.

Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Acked-by: Andy Neitzke <neitzke@ias.edu>

Signed-off-by: Alexey Starikovskiy <astarikovskiy <at> suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
2008-12-22 19:32:55 -05:00
Linus Torvalds
f10a3a32ae Revert "ACPI: battery: Convert discharge energy rate to current properly"
This reverts commit 558073dd56, along with
the failed try to fix the regression it caused ("ACPI: Fix ACPI battery
regression introduced by commit 558073"), which just made things worse.

Commit aaad077638 (that failed "Fix ACPI
battery regression") got the voltage conversion confused, and fixed the
problem with Rafael's battery monitor apparently just by mistake.

So revert them both, getting us back to the 2.6.27 state in this, and
let's revisit it when people understand what's going on.

Noted-by: Paul Martin <pm@debian.org>
Requested-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Len Brown <len.brown@intel.com>
Cc: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-12-05 13:30:03 -08:00
Rafael J. Wysocki
aaad077638 ACPI: Fix ACPI battery regression introduced by commit 558073
Commit 558073dd56 ("ACPI: battery: Convert
discharge energy rate to current properly") caused the battery subsystem
to report wrong values of the remaining time on battery power and the
time until fully charged on Toshiba Portege R500 (and presumably on
other boxes too).

Fix the issue by correcting the conversion from mW to mA.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-12-04 21:43:16 -08:00
Alexey Starikovskiy
558073dd56 ACPI: battery: Convert discharge energy rate to current properly
ACPI battery interface reports its state either in mW or in mA, and
discharge rate in your case is reported in mW. power_supply interface
does not have such a parameter, so current_now parameter is used
for all cases. But in case of mW, reported discharge should
be converted into mA.

Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Tested-by: Ferenc Wagner <wferi@niif.hu>
Signed-off-by: Len Brown <len.brown@intel.com>
2008-11-26 17:23:10 -05:00
Len Brown
9b5a56ddfd Merge branch 'sysfs' into release 2008-11-11 21:14:49 -05:00
Bjorn Helgaas
89595b8f28 ACPI: consolidate ACPI_*_COMPONENT definitions in acpi_drivers.h
Move all the component definitions for drivers to a single shared place,
include/acpi/acpi_drivers.h.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>
2008-11-07 21:44:37 -05:00
Kay Sievers
0794469da3 ACPI: struct device - replace bus_id with dev_name(), dev_set_name()
This patch is part of a larger patch series which will remove
the "char bus_id[20]" name string from struct device. The device
name is managed in the kobject anyway, and without any size
limitation, and just needlessly copied into "struct device".

To set and read the device name dev_name(dev) and dev_set_name(dev)
must be used. If your code uses static kobjects, which it shouldn't
do, "const char *init_name" can be used to statically provide the
name the registered device should have. At registration time, the
init_name field is cleared, to enforce the use of dev_name(dev) to
access the device name at a later time.

We need to get rid of all occurrences of bus_id in the entire tree
to be able to enable the new interface. Please apply this patch,
and possibly convert any remaining remaining occurrences of bus_id.

We want to submit a patch to -next, which will remove bus_id from
"struct device", to find the remaining pieces to convert, and finally
switch over to the new api, which will remove the 20 bytes array
and does no longer have a size limitation.

Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-Off-By: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Len Brown <len.brown@intel.com>
2008-11-06 21:37:19 -05:00
Len Brown
057316cc6a Merge branch 'linus' into test
Conflicts:
	MAINTAINERS
	arch/x86/kernel/acpi/boot.c
	arch/x86/kernel/acpi/sleep.c
	drivers/acpi/Kconfig
	drivers/pnp/Makefile
	drivers/pnp/quirks.c

Signed-off-by: Len Brown <len.brown@intel.com>
2008-10-23 00:11:07 -04:00
Parag Warudkar
01e8ef11bc x86: sysfs: kill owner field from attribute
Tejun's commit 7b595756ec made sysfs
attribute->owner unnecessary.  But the field was left in the structure to
ease the merge.  It's been over a year since that change and it is now
time to start killing attribute->owner along with its users - one arch at
a time!

This patch is attempt #1 to get rid of attribute->owner only for
CONFIG_X86_64 or CONFIG_X86_32 .  We will deal with other arches later on
as and when possible - avr32 will be the next since that is something I
can test.  Compile (make allyesconfig / make allmodconfig / custom config)
and boot tested.

akpm: the idea is that we put the declaration of sttribute.owner inside
`#ifndef CONFIG_X86'.  But that proved to be too ambitious for now because
new usages kept on turning up in subsystem trees.

[akpm: remove the ifdef for now]
Signed-off-by: Parag Warudkar <parag.lkml@gmail.com>
Cc: Greg KH <greg@kroah.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Tejun Heo <htejun@gmail.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: Roland Dreier <rolandd@cisco.com>
Cc: David Brownell <david-b@pacbell.net>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-20 08:52:42 -07:00
Pavel Machek
db89b4f0db ACPI: catch calls of acpi_driver_data on pointer of wrong type
Catch attempts to use of acpi_driver_data on pointers of wrong type.

akpm: rewritten to use proper C typechecking and remove the
"function"-used-as-lvalue thing.

Signed-off-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Len Brown <len.brown@intel.com>
2008-10-10 18:05:53 -04:00
Denis V. Lunev
cf7acfab03 acpi: use non-racy method for proc entries creation
Use proc_create()/proc_create_data() to make sure that ->proc_fops and ->data
be setup before gluing PDE to main tree.

Add correct ->owner to proc_fops to fix reading/module unloading race.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-29 08:06:22 -07:00
Alexey Starikovskiy
b8a1bdb149 ACPI: battery: Don't return -EFAIL on broken packages.
Acer BIOS has a bug which is exposed when a dead battery is present.

The package template that is used to describe battery status is
over-written with sane values when the battery is live.
But when the batter is dead, a bogus reference in the template
is used.  In this case, Linux returns a fault, when instead
it should simply return that it doesn't know the missing value.

http://bugzilla.kernel.org/show_bug.cgi?id=8573
http://bugzilla.kernel.org/show_bug.cgi?id=10202

Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
2008-03-17 22:37:42 -04:00
maximilian attems
7c2670bbb5 ACPI: battery: add sysfs serial number
egrep serial /proc/acpi/battery/BAT0/info
serial number:           32090

serial number can tell you from the imminent danger
of beeing set on fire.

Signed-off-by: maximilian attems <max@stro.at>
Acked-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
2008-02-05 21:15:50 -05:00
Alexey Starikovskiy
97749cd9ad ACPI: Make sysfs interface in ACPI power optional.
Reference: http://bugzilla.kernel.org/show_bug.cgi?id=9494

Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
2008-01-01 14:27:24 -05:00
Andrey Borzenkov
ad40e68bf5 ACPI: battery: fix ACPI battery technology reporting
At least some systems report technology information with trailing spaces:

{pts/1}% cat -E /var/tmp/bat/2.6.23 | grep type
battery type:            Li-ION  $

Use strncasecmp to compare model string to skip trailing part

Signed-off-by: Andrey Borzenkov <arvidjaar@mail.ru>
Acked-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
2007-12-06 22:29:22 -05:00
Len Brown
c2e46d2e2a Pull procfs-default into release branch
Conflicts:

	drivers/acpi/sbs.c

Signed-off-by: Len Brown <len.brown@intel.com>
2007-11-20 01:20:00 -05:00
Len Brown
86533e80e0 Pull battery into release branch 2007-11-20 01:17:42 -05:00
Alexey Starikovskiy
fdcedbba2f ACPI: Split out control for /proc/acpi entries from battery, ac, and sbs.
Introduce new ACPI_PROCFS_POWER (default Yes) config option and move
procfs code in battery, ac, and sbs drivers under it.
This is done to allow ACPI_PROCFS to be default No.

Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
2007-11-19 11:21:50 -05:00
Alexey Starikovskiy
9104476e4e ACPI: Battery: remove cycle from battery removal.
get_property() should not call battery_update(), it also should call
get_status() only if battery is present to avoid cycle and oops.

Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Tested-by: Rolf Eike Beer <eike-kernel@sf-tec.de>
Acked-by: Johannes Weiner <hannes@saeurebad.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-11-13 09:02:18 -08:00
Roland Dreier
4c41d3ad65 ACPI: Always return valid 'status' from acpi_battery_get_property()
If a battery is at a critical charge level and not being charged or
discharged, then the ACPI _BST method will return a state of 4, and
the current acpi_battery_get_property() code will not set any property
value for POWER_SUPPLY_PROP_STATUS.  This will cause an oops in
power_supply_show_property() when it reads off the end of the
status_text array.  This actually was causing a 100% reproducible
crash on boot on my laptop with two batteries, when one battery was
completely drained and the laptop was not plugged in.

Fix this by making sure acpi_battery_get_property() returns
POWER_SUPPLY_STATUS_UNKNOWN for any battery state it doesn't already
handle explicitly.  There doesn't seem to be any status enum value
defined that makes more sense than 'unknown' for a battery at a
critical charge level.

Signed-off-by: Roland Dreier <roland@digitalvampire.org>
Acked-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <lenb@t61.(none)>
2007-11-08 15:08:15 -05:00
Alexey Starikovskiy
106449e870 ACPI: Battery: Allow extract string from integer
Some machines return integer instead of expected string.

Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Tested-by: Andrey Borzenkov <arvidjaar@mail.ru>
Tested-by: Frans Pop <elendil@planet.nl>
Signed-off-by: Len Brown <len.brown@intel.com>
2007-10-29 16:52:01 -04:00
Alexey Starikovskiy
0bde7eee94 ACPI: battery: Support for non-spec name for LiIon technology
Support Li-Ion as possible name for technology.

Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
2007-10-29 16:33:22 -04:00
Andrey Borzenkov
508df92d1f ACPI: battery: register power_supply subdevice only when battery is present
Make sure no power_supply object is present unless we actualy detect
presence of battery. This fixes ghost batteries detected by HAL

Signed-off-by: Andrey Borzenkov <arvidjaar@mail.ru>
Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
2007-10-29 16:30:23 -04:00
Alexey Starikovskiy
b19073a0be ACPI: battery: Update battery information upon sysfs read.
Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
2007-10-25 17:10:47 -04:00
Adrian Bunk
c9e4172cde ACPI: battery: remove dead code
After commit f1d4661abe this was dead
code.

Spotted by the Coverity checker.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Acked-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
2007-10-25 16:33:00 -04:00
Alexey Starikovskiy
3e58ea0d31 ACPI: Battery: add sysfs alarm
Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
2007-09-27 15:50:22 -04:00
Alexey Starikovskiy
d738096575 ACPI: Battery: Add sysfs support
Refer to Documentation/power_supply_class.txt for interface description.

Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
2007-09-27 15:50:22 -04:00
Alexey Starikovskiy
aa650bbdcb ACPI: Battery: Misc clean-ups, no functional changes
Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
2007-09-27 15:50:21 -04:00
Alexey Starikovskiy
f1d4661abe ACPI: Battery: simplify update scheme
Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
2007-09-27 15:50:21 -04:00
Alexey Starikovskiy
038fdea296 ACPI: Battery: don't use acpi_extract_package()
acpi_extract_package() creates more problems with memory management than
it solves as helper for package handling.

Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
2007-09-27 15:50:21 -04:00
Len Brown
25c87f7f2a Pull events into release branch
Conflicts:

	drivers/acpi/video.c

Signed-off-by: Len Brown <len.brown@intel.com>
2007-08-25 01:44:01 -04:00
Len Brown
14e04fb34f ACPI: Schedule /proc/acpi/event for removal
Schedule /proc/acpi/event for removal in 6 months.

Re-name acpi_bus_generate_event() to acpi_bus_generate_proc_event()
to make sure there is no confusion that it is for /proc/acpi/event only.

Add CONFIG_ACPI_PROC_EVENT to allow removal of /proc/acpi/event.
There is no functional change if CONFIG_ACPI_PROC_EVENT=y

Signed-off-by: Len Brown <len.brown@intel.com>
2007-08-23 15:20:26 -04:00
Zhang Rui
962ce8ca06 ACPI: don't duplicate input events on netlink
The previous events patch added a netlink event for every
user of the legacy /proc/acpi/event interface.

However, some users of /proc/acpi/event are really input events,
and they already report their events via the input layer.

Introduce a new interface, acpi_bus_generate_netlink_event(),
which is explicitly called by devices that want to repoprt
events via netlink.  This allows the input-like events
to opt-out of generating netlink events.  In summary:

events that are sent via netlink:
	ac/battery/sbs
	thermal
	processor
	thinkpad_acpi dock/bay

events that are sent via input layer:
	button
	video hotkey
	thinkpad_acpi hotkey
	asus_acpi/asus-laptop hotkey
	sonypi/sonylaptop

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
2007-08-23 14:27:23 -04:00
Len Brown
5b31d89587 Revert "ACPI: Battery: Synchronize battery operations."
This reverts commit 3bd92ba19a.

It is no longer necessary, and it opens up a race.

Acked-by: Vladimir Lebedev <vladimir.p.lebedev@gmail.com>
Acked-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
2007-08-15 00:19:26 -04:00
Alexey Starikovskiy
3bd92ba19a ACPI: Battery: Synchronize battery operations.
http://bugzilla.kernel.org/show_bug.cgi?id=8768

Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
2007-08-03 17:38:20 -04:00
Thomas Renninger
1ba90e3a87 ACPI: autoload modules - Create __mod_acpi_device_table symbol for all ACPI drivers
modpost is going to use these to create e.g. acpi:ACPI0001
in modules.alias.

Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
2007-07-23 13:56:42 -04:00
Alexey Starikovskiy
78490d8212 ACPI: battery: syntax cleanup
In response to review comments from Andrew Morton

Signed-off-by: Alexey Starikovskiy <aystarik@gmail.com>
Signed-off-by: Len Brown <len.brown@intel.com>
2007-05-11 13:18:55 -04:00
Vladimir Lebedev
6eedeef73e process reading battery status hangs
http://bugzilla.kernel.org/show_bug.cgi?id=8351

Signed-off-by: Vladimir Lebedev <vladimir.p.lebedev@gmail.com>
Signed-off-by: Len Brown <len.brown@intel.com>
2007-04-21 22:41:48 -04:00
Vladimir Lebedev
9ea7d57576 ACPI: battery: Lindent
Signed-off-by: Vladimir Lebedev <vladimir.p.lebedev@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
2007-03-07 01:48:11 -05:00
Vladimir Lebedev
b6ce4083ed ACPI: Cache battery status instead of re-evaluating AML
/proc exports _BST in a single file, and _BST is re-evaulated
whenever that file is read.

Sometimes user-space reads this file frequently, and on some
systems _BST takes a long time to evaluate due to a slow EC.

Further, when we move to sysfs, the values returned from _BST
will be in multiple files, and evaluating _BST for each
file read would make matters worse.

Here code is added to support caching the results of _BST.
A new module parameter "update_time" tells how many seconds the
cached _BST should be used before it is re-evaluated.
Currently, update_time defaults to 0, and so the
existing behaviour of re-evaluating on each read retained.

Signed-off-by: Vladimir Lebedev <vladimir.p.lebedev@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
2007-03-07 01:48:07 -05:00